package madixin.t617;

class Solution {
    public TreeNode mergeTrees(TreeNode t1, TreeNode t2) {

        if (t1 == null) {
            return t2;
        } else if (t2 == null) {
            return t1;
        } else {
            TreeNode node = new TreeNode(t1.val + t2.val);
            node.left = mergeTrees(t1.left, t2.left);
            node.right = mergeTrees(t1.right, t2.right);
            return node;
        }
    }
}